Stress or something more?

[Crystal_Marie]

I noticed my betta has what look like stress stripes but also has this white vertical patch. She has had a faint vertical line of white scales before but it’s more distinct. 
 

tank info:

temp: 78.2°F

filtered with 2 sponge filters + air stones 

Cycled planted 29gal tank 

pH 7.6-7.8

ammonia and nitrites 0

nitrates 5

kh 120-180 but stable 

gh 150-200 but stable

tank mates: 6 panda corydoras that were fully quarantined for 4 weeks with the ACO recommended medication trio.
 

since adding corys, my betta has become food aggressive. She doesn’t fuss with the corys except at meal times. So I feed her in an iso/nursing box for 20-30 mins while the corys eat. She doesn’t like their food but will chase them away from it. So now I’m concerned that she’s stressing herself sick. Normally I would’ve added her after the corys but that wasn’t a feasible option. Other than the food aggression her behavior/swimming/appetite has not changed.
Any advice would be appreciated. 

[JessLynne7]

My bettas stress stripes were red and horizontal. Just speaking from my experience.

it’s hard to tell from the pic but the stripe is it white and fuzzy or is it just the way the picture looks.

 

you can take her out for a bit and re arrange the tank and then re introduce her. 
you can also try distracting her while the other fish eat 

[Colu]

Could be the start of Columnaris I would do a course of kanaplex in food feeding a small amount twice a day for 7 days if you notice the white patch start to spread then I would treat with a combination of kanaplex and jungal fungas clear fizz tabs containing nitrofurazone together following this treatment schedule